How Much Protection Is Enough? -- Ask yourself these five questions concerning ESD protection-you might not like your answers.

One of the most frequently asked questions in static control is straightforward and basic, "How much protection is enough?" The question is usually triggered by the need to make certain choices: "If I have wrist straps, do I need electrostatic discharge (ESD) flooring? Do I really need ionization? What about garments and footwear?" The protection issue is further impacted by financial considerations.

The question may seem rather simple, but the answer is not. Actually, two answers exist-answers that most ESD managers don't want to hear-"Enough to do the job." and "It depends." Unfortunately, the issue is not a simple black and white situation, as much as we might like it to be.

The new ESD control program standard, ANSI/ESD S20.20, goes a long way in providing program guidance for protecting devices and assemblies that are sensitive to 100 V human body model (HBM) discharges. But, the document recognizes that ESD control programs require tailoring for specific needs and applications. Therefore, the standard provides a number of options.

To discover how much protection is enough, evaluate your manufacturng environment to understand possible static control problems. Ask yourself a few simple questions:

1. What is the ESD sensitivity of the devices and assemblies that we handle? Products that are sensitive to 100V HBM discharges require different protection than those that are sensitive to 1,000V HBM discharges.

2. What is the value of the final product and what are the company's annual losses to ESD? The degree of protection is directly influenced by product cost and product losses. Find out the return on investment in static control for your operation, not someone else's.

3. What is the risk of inadequate protection? Find out whether or not your quality and inspection system is adequate enough to prevent damaged parts from being shipped. Is it less expensive to prevent damage or to discard damaged parts? You could be risking current and future business if you ship damaged products.

4. Which areas of the process provide the greatest ESD exposure to our products? Discover where the potential problem areas in your operation lie-truly a key to determining how much protection is enough.

If your manufacturing process is primarily automated assembly, and you are not experiencing significant problems in the manufacturing area, protective flooring in this area may not be warranted. If, however, you are experiencing significant problems in your rework area, problems may occur due to personnel handling products while seated at workstations. The solution is to implement wrist straps and protective worksurfaces. If you also experience damage from highly mobile personnel, as they move through the area, add protective flooring and footwear to reduce ESD generation. If the source of the problem is created by electrostatic fields from insulators in the area, topical antistats or ionizers also may be needed.

5. Do you need to audit and evaluate your efforts? You may find that the additional static control material or procedures did not solve your ESD problems. Or, you may find that changes in the area increased your ESD exposure. Hopefully, the corrections made will greatly improve the situation.

How much protection is enough? The answer lies in knowing and understanding your processes and facility to develop and implement the program that meets your specific needs.

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Michael T. Brandt is is publicity consultant to the ESD Association and president of Marketing Re-sources Ltd., Lakewood, CO; e-mail: [e-mail]. This column is a regular contribution of the ESD Association, Rome, NY; [phone]; e-mail: [e-mail].

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